NEW YORK (Reuters Health) - Obese children who watch a lot of television are more likely to have high blood pressure than heavy children who don't spend as much time in front of the tube, the results of a new study shows.

Increased psychological stress and junk food eaten while watching TV could be factors in the relationship, principal investigator Dr. Jeffrey B. Schwimmer of the University of California, San Diego, told Reuters Health.

Obese children who watched 2 to 4 hours of TV each day were 2.5 times more likely than their peers who watched less TV to have high blood pressure, he and his colleagues found, while kids who watched more than 4 hours daily had more than triple the risk of having high blood pressure.

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TV watching time clearly influences obesity and high blood pressure is a known consequence of obesity, Schwimmer and his team point out in the American Journal of Preventive Medicine.

To investigate this relationship, they evaluated 546 children between 4 and 17 years old who were seeking treatment for obesity. Forty-three percent had high blood pressure.

Most of the study participants with high blood pressure watched 2 hours or more of television. Time spent watching television was also associated with the severity of obesity, the researchers found.

Kids who watch more TV may also be eating more fatty, salty foods, which could directly contribute to high blood pressure, Schwimmer and his colleagues note.

Studies have shown that children who watch more TV experience more perceived psychological stress, Schwimmer noted, and evidence is mounting that stress can alter how the brain communicates with other organs, affecting blood pressure and body fat accumulation and distribution.

The findings underscore the importance of limiting children's TV viewing to less than 2 hours a day, as recommended by the American Academy of Pediatrics, he said, and that this may be particularly important for overweight and obese children.

Blood pressure is often not measured in children, and if it is measured, "it's often not done correctly," Schwimmer added. "I would encourage parents of children to raise the issue of blood pressure with their child's doctor."